Conventionally, there has been suggested a vehicular lamp having a combination of a light source (e.g., an LED) and a plate-shaped light guide for controlling light from the light source. The light emitted from the light source is incident on the light guide. The light incident on the light guide is, for example, reflected, refracted, and scattered by components of the light guide such as, for example, an incident surface and a reflecting surface, and is emitted from a predetermined emitting surface. As a result, it seems to a person who is outside the vehicle that the entire light guide is emitting light. See, e.g., Japanese Patent Laid-Open Publication No. 2014-167879.